1. Based on your homework reading, what is an enzyme?

2. Some reactions have enzymes. What might be an advantage to having enzymes in chemical reactions? Any disadvantages?

3. Can you name any enzymes?

BELLRINGER-3/9/15

ENZYMES

Most enzymes are proteinsAct as a catalyst to speed up a

chemical reaction by helping molecules react with each other faster

WHAT IS AN ENZYME?

Reusable!Specific for what they catalyze (speed up)

End in “-ase”Named for the reaction they help. For example…Sucrase breaks down sucroseProteases break down proteinsLipases break down lipidsDNA polymerase builds DNA

ENZYMES ARE…

Lactase breaks down lactose, a common component of dairy products (like milk)

People lacking the enzyme lactase are considered “lactose intolerant”-they can’t digest large amounts of milk!!

CASE STUDY: LACTOSE INTOLERANCE

Re-used again for the same reaction with other molecules

Very little enzyme is needed to help in many reactions!

ENZYMES ARE NOT USED UP!

Products

Substrate

Active Site

Enzyme

Remember, enzymes are specific!

Lock and Key Model: Shape of enzyme allows substrate to fitSpecific enzyme for each specific reaction

LOCK AND KEY MODEL

Chemical ReactionEnzyme + Substrate Enzyme + Product

REACTANTS PRODUCTS

Enzymes work by weakening bonds, which lowers ACTIVATION ENERGYActivation Energy=energy needed for the chemical reaction to occur (energy needed to activate!)

By lowering the activation energy, the reaction can occur faster!

SO…HOW DO ENZYMES WORK?

Reactions can occur without the help…but not at the speed our bodies need!

TemperatureHigh temperatures can cause enzymes to denature (unfold and lose shape), while low temperatures slow molecules down

pHChanges in pH changes protein shape (most human proteins sit at a pH of 6-8)

Denaturing=extreme temperature and pH can change enzyme shape, rendering it useless!

WHAT EFFECTS ENZYME ACTIVITY?

Every reaction in your body is helped by an enzyme. They are necessary for all biological reactions!

WHY ARE ENZYMES IMPORTANT?

Energy in the cellPHOTOSYNTHESIS

Process that uses the sun’s energy to make glucose (food for the plant)

Performed in: Green plants and some bacteria

Occurs in the chloroplasts of the plant cell

WHAT IS PHOTOSYNTHESIS?

PHOTOSYNTHESIS FORMULA

6CO2 + 6H2O C6H12O6 + 6O2Carbon dioxide water glucose oxygen

The rate (speed) at which a plant performs photosynthesis is based on a number of things:

# of reactantsMore reactants yields more products

Temperature and pHRecall that enzymes are directly impacted by these factors!

LightNo light=no photosynthesis

RATE OF PHOTOSYNTHESIS

Energy in the Cell

CELLULAR RESPIRATION

Process where molecules of glucose are broken down to make CO2, water, and ATP

Occurs in the mitochondria of eukaryotes

WHAT IS CELLULAR RESPIRATION?

RESPIRATION FORMULA

C6H12O6 + 6O2 6CO2 + 6H2O + ATP glucose oxygen carbon dioxide water energy

The point of cellular respiration is to make ATP!ATP is ENERGYAll organisms require energy to live (movement, cell division, active transport, etc…)

CELLULAR RESPIRATION

Three phosphates

Adenine

Ribose

What do you notice about the relationship between the two processes?

PHOTOSYNTHESIS AND RESPIRATION

Comparing Energy Processes

AEROBIC VS. ANAEROBIC

RESPIRATION

Aerobic respiration takes place in the presence of oxygen

This is most effi cient-can produce up to 38 ATP per glucose!

Carried out in the mitochondria

AEROBIC RESPIRATION

BUT WHAT IF OXYGEN ISN’T AVAILABLE?

Anaerobic Respiration, like fermentation, occurs when oxygen is NOT present

Less effi cient-only 2 ATP produced!Occurs in anaerobic bacteria, yeast,

and muscle cellsCarried out in the cytoplasm

ANAEROBIC RESPIRATION

Alcoholic Fermentation

Occurs in bacteria, yeast

Makes EthanolUsed in making

bread, wine, and beer

Lactic Acid Fermentation

Occurs in muscle cells, bacteria

Makes Lactic Acid

WHAT IS FERMENTATION?

Anaerobic respiration can occur in muscle cells during vigorous physical activity

Once your cells begin to lack suffi cient oxygen, they will switch to lactic acid fermentation

Lactic acid buildup and muscle fatigue leads to cramping!

CASE STUDY: MUSCLE CRAMPS

AEROBIC VS. ANAEROBIC